Method and device for controlling a set of reconfigurable intelligent surfaces

Abstract

A method for controlling a set of reconfigurable intelligent surfaces. The method includes: selecting, from among the set, at least one surface as an “intermediate surface”, and at least one surface as a “main surface”, the selection being made so as to optimize a determined communication performance criterion for antennas situated in the geographical area served by each main surface; determining phase shifts of reflective elements of the at least one selected intermediate surface and at least one selected main surface; and controlling reflective elements of the at least one intermediate surface and at least one main surface, both selected by using the determined phase shifts.

1 . A method for controlling a set of reconfigurable intelligent surfaces associated with an access point, said method being implemented by an electronic device and including:
 selecting, from among the set, at least one surface as an “intermediate surface” and at least one surface as a “main surface”, each surface of the set being associated with a given geographical area covered by the access point and which the surface is intended to serve if the surface is selected as main surface, each intermediate surface being positioned between the access point and a main surface and also intended to reflect toward said main surface signals emitted by the access point to exchange data with at least one user terminal situated in the geographical area served by said main surface, the selection being made so as to optimize a determined communication performance criterion for at least one user terminal in the geographical area served by each main surface,   determining phase shifts of reflective elements of said at least one selected intermediate surface and at least one selected main surface, and   controlling reflective elements of said at least one intermediate surface and at least one main surface, both selected by using the determined phase shifts.   
     
     
         2 . The method as claimed in  claim 1 , wherein the selecting, determining the phase shifts and controlling form a set of steps, said set of steps being iterated. 
     
     
         3 . The method as claimed in  claim 2 , wherein said set of steps is iterated according to a determined time increment corresponding to a coherence time associated with the signals emitted by the access point, or with a determined slot of the coherence time. 
     
     
         4 . The method as claimed in  claim 1 , wherein the communication performance criterion is representative of at least one element from among:
 a bitrate of the data which can be exchanged between the access point and at least one user terminal situated in the geographical area served by each main surface,   a level of quality of service of the exchanges of data between the access point and at least one user terminal situated in the geographical area served by each main surface,   an energy required to carry out exchanges of data between the access point and at least one user terminal situated in the geographical area served by each main surface,   a signal-to-noise ratio of the exchanges of data between the access point and at least one user terminal situated in the geographical area served by each main surface.   
     
     
         5 . The method as claimed in  claim 1 , wherein the optimization of the performance criterion takes into account, as optimization variable and for at least one user terminal situated in the geographical area served by a main surface, a parameter representative of whether said at least one user terminal is served or not. 
     
     
         6 . The method as claimed in  claim 1 , said method including, prior to the selecting, determining, for each surface of the set, the user terminals to be served by said surface if the surface is selected as main surface. 
     
     
         7 . The method as claimed in  claim 3 , wherein said time increment corresponding to the coherence time, said coherence time being sampled into a plurality of determined slots, the optimization of the performance criterion taking into account, as optimization variable and for each surface of the set, a parameter representative of the number of slots of the coherence time during which said surface is selected as main surface. 
     
     
         8 . The method as claimed in  claim 1 , wherein the optimization of the performance criterion is parameterized such that:
 selection of a plurality of main surfaces is allowed, and   the intermediate surface or surfaces selected to reflect signals toward one main surface are distinct from the intermediate surface or surfaces selected to reflect signals toward another main surface.   
     
     
         9 . The method as claimed in  claim 1 , wherein the determining the phase shifts is implemented such that a power of the signals reflected by an intermediate surface toward a main surface is greater than a given threshold or maximized, said power being a function parameterized by said phase shifts, angles of the signals emitted by the access point toward said intermediate surfaces as well as angles of departure of the signals reflected by said intermediate surface toward said main surface. 
     
     
         10 . The method as claimed in  claim 9 , wherein the phase shifts are also determined such that the power of signals reflected by an intermediate surface directly toward at least one user terminal situated in the geographical area served by the main surface toward which signals are reflected by said intermediate surface is less than a given threshold or minimized. 
     
     
         11 . The method as claimed in  claim 9 , wherein the phase shifts are also determined such that the power of signals reflected by an intermediate surface toward at least one other intermediate surface is less than a given threshold or minimized. 
     
     
         12 . A non-transitory computer-readable recording medium on which is recorded a computer program which when executed by a processor of the electronic device, configure the electronic device to perform the method as claimed in  claim 1 . 
     
     
         13 . A control device comprising:
 at least one processor; and   at least one non-transitory computer readable medium comprising instructions stored thereon which when executed by the at least one processor configure the control device to control a set of reconfigurable intelligent surfaces associated with an access point by:   selecting, from among the set, at least one surface as an “intermediate surface” and at least one surface as a “main surface”, each surface of the set being associated with a given geographical area covered by the access point and which the surface is intended to serve if the surface is selected as main surface, each intermediate surface being positioned between the access point and a main surface and also intended to reflect toward said main surface signals emitted by the access point to exchange data with at least one user terminal situated in the geographical area served by said main surface, the selection being made so as to optimize a determined communication performance criterion for at least one user terminal in the geographical area served by each main surface;   determining phase shifts of reflective elements of said at least one selected intermediate surface and at least one selected main surface; and   controlling reflective elements of said at least one intermediate surface and at least one main surface, both selected by using the determined phase shifts.   
     
     
         14 . A method for controlling a set of reconfigurable intelligent surfaces associated with an access point, said method being implemented by an electronic device and including:
 selecting, from among the set, at least one surface as an “intermediate surface” and at least one surface as a “main surface”, each surface of the set being associated with a given geographical area covered by the access point and from which the surface is intended to receive signals emitted by at least one user terminal to exchange data with the access point if the surface is selected as a main surface, each intermediate surface being positioned between the access point and a main surface from which the intermediate surface is intended to receive signals to reflect them toward the access point, the selection being made so as to optimize a determined communication performance criterion for at least one user terminal situated in the geographical area served by each main surface,   determining phase shifts of reflective elements of said at least one selected intermediate surface and at least one selected main surface,   controlling the reflective elements of said at least one intermediate surface and at least one main surface, both selected by using the determined phase shifts.   
     
     
         15 . The method as claimed in  claim 14  wherein the selecting, determining the phase shifts and controlling form a set of steps, said set of steps being iterated. 
     
     
         16 . The method as claimed in  claim 15 , wherein said set of steps is iterated according to a determined time increment corresponding to a coherence time associated with the signals emitted by said at least one user terminal, or with a determined slot of the coherence time. 
     
     
         17 . The method as claimed in  claim 14 , wherein the optimization of the performance criterion takes into account, as optimization variable and for at least one user terminal situated in the geographical area served by a main surface, a parameter representative of whether said at least one user terminal is served or not. 
     
     
         18 . The method as claimed in  claim 14 , said method including, prior to the selecting, determining, for each surface of the set, the user terminals to be served by said surface if the surface is selected as main surface. 
     
     
         19 . The method as claimed in  claim 14 , wherein the determining the phase shifts is implemented such that a power of the signals reflected by an intermediate surface toward the access point is greater than a given threshold or maximized, said power being a function parameterized by said phase shifts, angles of the signals reflected by said at least one main surface toward said intermediate surface as well as angles of the signals reflected by said intermediate surface toward the access point. 
     
     
         20 . The method as claimed in  claim 19 , wherein the phase shifts are also determined such that the power of signals reflected by an intermediate surface directly toward at least one user terminal situated in the geographical area served by the main surface toward which signals are reflected by said intermediate surface is less than a given threshold or minimized.